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Abstract

Purpose

To examine the effect of betaine supplementation on cycling sprint performance.

Methods

Sixteen recreationally active subjects (7 females and 9 males) completed three sprint
tests, each consisting of four 12 sec efforts against a resistance equal to 5.5% of
body weight; efforts were separated by 2.5 min of cycling at zero resistance. Test
one established baseline; test two and three were preceded by seven days of daily
consumption of 591 ml of a carbohydrate-electrolyte beverage as a placebo or a carbohydrate-electrolyte
beverage containing 0.42% betaine (approximately 2.5 grams of betaine a day); half
the beverage was consumed in the morning and the other half in the afternoon. We used
a double blind random order cross-over design; there was a 3 wk washout between trials
two and three. Average and maximum peak and mean power were analyzed with one-way
repeated measures ANOVA and, where indicated, a Student Newman-Keuls.

Conclusions

One week of betaine ingestion improved cycling sprint power in recreationally active
males and females.

Keywords:

Anaerobic power; Ergogenic aid; Creatine; Wingate

Background

Betaine is a nutrient found in a variety of animals, plants, and microorganisms [1]. It is a component of many foods, with whole grains (e.g., wheat, rye), spinach,
shellfish and beets [2] being rich sources. As an organic osmolyte, betaine or trimethyl glycine, protects
cells under stress, such as dehydration; it is also a source of methyl groups, via
the methionine cycle, in many key biochemical pathways [1]. Betaine, therefore, plays an important role in several aspects of human health and
nutrition and studies show that diets high in betaine decrease disease risk [1,3-5].

In addition to improving health, betaine may also improve sport performance. Since
betaine is an osmolyte that protects cells under stress [6,7], initial studies on the potential ergogenicity focused on the acute effects of betaine
ingestion on performance in the heat [8,9]. In one study, subjects ran in a heated environment (31.1°C) for 75 minutes at 65%
of VO2max followed by a performance run at 84% of VO2max to volitional exhaustion [8]. Time to exhaustion was 16 to 21% (32 to 38 sec) greater when beverages with betaine
or betaine and carbohydrate were consumed, respectively, but the changes were statistically
insignificant (p ≥ 0.12). In the other study, subjects completed a 15 min cycling
time trial after riding for 2 hr at 60-75% VO2max in the heat [9]; immediately after the time trial, isometric leg strength was also examined. Acute
consumption of either a carbohydrate or a betaine and carbohydrate beverage before
the test improved time trial performance by 10 and 14%, respectively, relative to
a water control trial; there was no difference between the carbohydrate and carbohydrate
and betaine trials. Isometric leg strength, however, was significantly greater after
the betaine trials compared to the non-betaine trials.

This latter result catalyzed a series of inquires on the chronic effects of betaine
ingestion (2 weeks) on various indices of strength and power [10,11]. The assumption being that since betaine is a methyl donor [1], it could theoretically boost creatine stores in the musculature, and therefore,
improve strength and power [10]. Chronic betaine ingestion (at least 2.5 g.d-1 for 14 d) significantly improved bench press repetitions, volume load, throw power,
isometric bench press force, vertical jump power, isometric squat force, and muscle
endurance during a squat exercise [10-12]. Despite enhancing the aforementioned indices of lower extremity strength and power,
chronic betaine ingestion did not improve Wingate anaerobic power [10]. The inability of betaine to enhance cycling sprint performance, as measured with
the Wingate anaerobic power test, may be related to the duration of the test and the
amount of recovery between trials. Perhaps the 30 sec Wingate test and the 5 min recovery
period between trials were too long to fully assess betaine's putative ability to
enhance sport specific strength and power, both of which contribute significantly
to Wingate performance. A series of shorter work bouts interspersed with shorter periods
of active recovery may be a more applicable test of betaine's potential to enhance
anaerobic power while cycling. To that end, our purpose was to examine the effect
of one week of betaine ingestion on anaerobic power as measured with a series of four,
12 sec work bouts on the cycle ergometer.

Methods

Subjects

Sixteen college-aged males (n = 9) and females (n = 7) volunteered to participate
in this study; their mean ± SD for age, height, and weight were: 19 ± 0.8 y, 172 ±
12.0 cm, and 75 ± 14.9 kg and morphological data are present in Table 1. All subjects were free of lower body musculoskeletal injury and reported no limitations
to exercise. Subjects were informed of the experimental procedures and known risks,
and signed an informed consent approved by the Ithaca College Human Subjects Review
Board prior to participation.

Experimental design

This investigation examined the effects of two drink solutions on cycling sprint performance
with a double blind cross-over design. The placebo was a commercial carbohydrate-electrolyte
beverage (Wegmans MVP), whereas the same carbohydrate-electrolyte beverage with 2.5
g of betaine (minimum purity is 99%; BetaPower™ DuPont Nutrition & Health, Tarrytown,
NY) was the experimental drink. Since betaine is colorless and tasteless, subjects
could not differentiate between the two solutions. Furthermore, to ensure drink anonymity,
all cap ties were broken prior to consumption. Subjects completed three cycling sprint
tests, the first of which served as a baseline measure. Subjects were match-paired
based upon maximum peak power and assigned to consume either the placebo or betaine
beverage. They were instructed to consume approximately half (295 mL) of their respective
beverage twice a day for seven days, after which they were tested again. The last
drink was consumed the morning of the test day and all testing sessions took place
in the evening. Following a three-week washout phase, a second seven day supplementation
period with the opposite beverage occurred followed by the third testing session.
Prior to every laboratory session, we used the Tanita 350 bioimedance body fat analyzer
to assess the subjects' weight, total body water, fat free mass, and percent body
fat (BF 350; Tanita Corporation of America, Inc. Arlington Heights, IL). This unit
is valid and reliable [13-16].

Performance testing

Prior to every sprint test, subjects pedaled at a self-selected pace against a light
resistance for 5 min to warm up with two to three interspersed sprints of short duration.
The sprint test followed which consisted of four, 12 sec work bouts on a Monark 834
E ergometer (Varberg, Sweden) against a resistance equal to 5.5% of body weight. Each
work bout was separated by 2.5 min of cycling at zero resistance. At the completion
of the test, subjects continued to pedal at zero resistance for 2.5 min to cool down.
The ergometer was equipped with toe clips, seat height was standardized for each subject
to allow for 10-15° of knee flexion, and vigorous verbal encouragement was provided
for all tests. SMI Power software (Sports Medicine Industries, St. Cloud, MN) interfaced
with the ergometer with an OptoSensor 2000 infrared sensor (Sports Medicine Industries,
St. Cloud, MN) collected data every second. The sensor was calibrated before every
testing session.

The following variables were measured during each sprint test: average peak power,
maximum peak power, average mean power, and maximum mean power. Average peak and average
mean power were calculated across the four work bouts in each sprint test; maximum
peak and mean power were the highest values for the respective variables in any sprint
test. Peak power was calculated as the highest power output over any five-second interval
during a sprint test. The coefficient of variation for average peak power, maximum
peak power, average mean power, and maximum mean power across two tests completed
on separate days was assessed in a series of pilot studies (n = 6) and were 1.3, 1.8,
1.3, and 1.6%, respectively.

Statistical analyses

Data were analyzed using one-way repeated measures ANOVA. Where indicated, a Student
Newman-Kuels test was used to identify specific differences (SigmaPlot v11, Systat
Software Inc, San Jose, CA); alpha was set at 0.05 for all tests. Data are presented
as mean ± SD.

Results

Based on the mean and SD for maximum peak power from the pilot study and an a priori
assumption that a 4% change in power pre- to post-supplementation is meaningful, we
used GPOWER software (Bonn, FRG) to determine that a sample size of 14 was needed
to give us a power of 0.80 with an alpha of 0.05. Table 2 shows the mean and SD for average peak power, maximum peak power, average mean power
and maximum mean power. Figures 1, 2, and 3 demonstrate mean and peak power across trials and gender. Compared to baseline, betaine
ingestion increased average peak power (6.4%; p < 0.001), maximum peak power (5.7%;
p < 0.001), average mean power (5.4%; p = 0.004), and maximum mean power (4.4%; p
= 0.004) for all subjects combined. Compared to placebo, betaine ingestion significantly
increased average peak power (3.4%; p = 0.026), maximum peak power (3.8%; p = 0.007),
average mean power (3.3%; p = 0.034), and maximum mean power (3.5%; p = 0.011) for
all subjects combined. There were no differences between the placebo and baseline
trials. There were no differences across time or between conditions for any of the
body composition variables.

Discussion

Our purpose was to examine the effect of one week of betaine ingestion on anaerobic
power as measured with a series of four, 12 sec work bouts. We found that one week
of betaine ingestion (2.5 g.d-1) improved sprint performance by 5.5 ± 0.8% compared to baseline and 3.5 ± 0.2% compared
to the carbohydrate placebo. These results contrast with data from Hoffman et al.
[10], who reported daily consumption of 2.5 grams of betaine mixed with a commercially
available carbohydrate beverage for 15 days did not enhance peak power, mean power,
rate of fatigue, or total work across two Wingate trials separated by 5 min of active
rest. One likely explanation for some of the difference in the results between the
studies is the nature of the sprint test. Our subjects completed more sprints (4 vs.
2) of a shorter duration (12 vs. 30 sec) that were interspersed with shorter periods
of active recovery (2.5 vs. 5 min) relative to the subjects in Hoffman et al. [10]. Experimental design may also account for some of the difference between the studies.
Hoffman et al. [10] used a randomized repeated measures design, whereas we used a cross-over repeated
measures design. Cross-over designs reduce the effects of confounding covariates and
are more efficient statistically.

The likely mechanisms behind the increased power output we measured are related to
methylation and osmolyte effects. Betaine supplementation may have elevated intramuscular
creatine stores, increased muscle growth, or protected the muscle cells from stress-induced
damage. The creatine hypothesis is attractive and supported by studies on betaine
metabolism. In short, the liver enzyme betaine homocysteine methyltransferase transfers
a methyl group from betaine to homocysteine, thereby producing dimethylglycine and
methionine. The latter is then converted to S-adenosylmethionine (SAM), which subsequently
acts as a methyl donor during creatine synthesis [17]. Studies show that betaine ingestion increases serum methionine, while betaine injection
increases red blood cell SAM concentrations [18,19]. Our observed changes in sprint performance, moreover, are consistent with the performance
effects of creatine supplementation, as shown in a meta-analysis [20]. Across 100 studies, creatine supplementation improved performance parameters by
5.7 ± 0.5% compared to baseline, whereas corresponding placebo effects were 2.4 ±
0.4%. More specifically, the meta-analysis showed that creatine supplementation improved
lower extremity power by 5.6 ± 0.6% relative to baseline, which is similar to the
5.5 ± 0.8% increase we measured.

It is unlikely, however, that the amount of betaine consumed by our subjects (2.5
g.d-1 for 7 d) elicits the same effect as the typical daily dosage of creatine during the
loading phase of approximately 25 grams. This conjecture is supported by recently
published data showing that 2 g.d-1 of betaine for 10 day did not increase phosphorylcreatine levels compared to 20 g.d-1 of creatine for 10 day [21]. This study also showed that betaine supplementation did not increase squat and bench
press 1 RM or bench and squat power, findings that are inconsistent with data from
earlier studies [10-12]. Direct comparison among the studies is difficult. Betaine dosage was lower in the
recent study (2 vs 2.5 g.d-1), supplementation time was shorter (10 vs 15 d) and power output was not assessed
until 3-5 d after supplementation ended compared to immediately afterwards [10,11].

Last, betaine supplementation may have enhanced sprint performance by acting as an
osmolyte to maintain cell hydration and function under stress more effectively than
placebo. Organic osmolytes are accumulated in cells when tissues are subjected to
stress [6,22]. They help cells maintain optimal osmotic pressure, and allow proteins to maintain
native folded conformation and stability without perturbing other cellular processes.
Betaine helps maintain cell homeostasis by preventing formation of stress granules
and keeping the mRNA associated machineries going under chronic hypertonicity [23]. Betaine is one of the most effective osmolytes, shown to facilitate a protective
monolayer of water around biopolymers, enhance muscle cell survival and protein synthesis,
and maintain myosin ATPase activity during periods of stress [24-26]. It may be that any or all of the aforementioned roles of betaine contributed to
the 5.5% increase in power we observed.

Conclusion

We found that one week of betaine supplementation increased peak and mean anaerobic
power by approximately 5.5% compared to baseline measures in recreationally active
college age men and women. The magnitude of this change is similar to the change in
anaerobic power following creatine supplementation. Future research should elucidate
the mechanism of improved performance via betaine supplementation.

Competing interests

JLP and TS declare that they have no competing interests and will not benefit from
the results of the present study. SASC is an employee of DuPont Nutrition & Health.
Publication of these findings should not be viewed as endorsement by the investigators,
Ithaca College, the University of Connecticut, or the editorial board of the Journal
of the International Society of Sport Nutrition.

Authors' contributions

JLP participated in drafting, editing, and submitting the manuscript. SASC assisted
with study design, statistical analysis and critically reviewed the manuscript for
intellectual content. TS supervised the research group, ran the statistical analysis,
interpreted data, and was involved with manuscript drafting. All authors read and
approved the final manuscript.

Acknowledgements

DuPont Nutrition & Health provided the BetaPower™ for the study. Authors would like
to thank Michael Aoun for supplying the carbohydrate-electrolyte drink and Riana R.
Pryor for her assistance with the study.